Tobacco composition and smoking unit containing material for eliminating deleterious matter



United States Patent G TOBACCO COMPOSITIGN AND SMOKING UNIT Thisinvention relates to smoking compositions and to smokable unitsincluding therein a novel particulate inorganic material intimatelyassociated with tobacco, the additives being capable of substantiallyreducing the quantity of tars normally generated during the burning ofthe tobaco and improving the aroma of tobacco. For many reasons,clinical and aesthetic, reduction in the tar yielded during the smokingof tobacco is highly desirable. First, there exists strong clinical,statistical and pathological evidence that certain constituents oftobacco smoke condensate (or tars as such condensate is usually termed)are potentially carcinogenic when deposited on human tissue. "thesecarcinogens have been reported to be mixtures of essentially neutralhigh-molecular weight polycyclic hydrocarbons, the carcinogenic potencyof any mixture depending on the species present. Several general typesof polycyclic aromatic hydrocarbons are usually present in tobacco smokecondensate and undoubtedly many individual molecular species are hencepresent. Deleterious polycyclic hydrocarbons are undoubtedly ofpyrogenic origin since they cannot be isolated from raw tobacco prior tothe pyrolysis thereof. These noxious substances are ordinarily carriedas dispersed droplets or solid particles in the effluent smoke streamand thence into the smokers respiratory system along with the aroma andtaste producing constituents of the smoke. Second- 1y, aside from theiralleged pathological effect, it appears that certain constituents oftars are responsible for the sharp irritating taste imparted to smokefrom a cigarette or the like. Furthermore, tars produce disfiguringcoloration of the teeth of many smokers and, if only for this reason,the lowering of total tars yielded during smoking is highly desirable.

Many elforts have been made in the past to reduce the yield of tars inthe efiiuent smoke of tobacco. The use of filter-tips, for example, hasmet widespread acceptance both by the cigarette industry and theconsumer. Another method involves the commingling with smoking tobaccoof particulate porous solids having high sorptivity by virtue of theirlarge specific surface, internal or external. The inclusion in smokingmixture of a variety of sorptive clays, colloidal and non-colloidal, andvarious forms of sorptive aluminous gels has been suggested in the priorart. Reduction of tobacco oils, nitrogenous bases and tars in the smokehave been among purported benefits although reproducible quantitativeevidence capable of being correlated with in vivo smoking conditions hasnot been set forth support of purported benefits. The tobacco industryhas apparently failed to find that the inclusion in tobacco compositionsof such particulate solids as have been proposed heretofore to be ofsuflicient value to warrent their use in commercial smoking mixtures.

It is apparent that smoking mixtures which include an innoxious additivewhich is capable of substantially lowering the tar yield of said tobaccowhen smoked meets a long-felt need of the tobacco smoker.

Accordingly, it is a principal object of the instant invention toprovide a composition including tobacco which incorporates a novelaluminous additive which functions 3,911,921 Patented Dec. 5, 1961 icethe quantity of tars in the smoke efiluent from said tobacco.

Another object of the invention is the provision of a compositionincluding tobacco intimately associated with an innoxious aluminousadditive capable at the elevated temperatures encountered in smokingtobacco of substantially lowering the yield of tars in the main streamsmoke of tobacco.

It is another important object to provide smoking units includingtobacco and a particulate aluminous additive dispersed through saidtobacco and capable of curtailing the quantity of tar generated duringpyrolysis of said tobacco.

Other objects will be apparent from a reading of a description of theinvention which follows.

I have discovered that substantial benefits are realized when certainclasses of crystalline aluminous materials are included in tobaccomixtures. Briefly, compositions of my invention comprise tobaccointimately associated with at least one crystalline form of aluminaselected from the group consisting of unfused alpha-alumina,gamma-alumina, transitional crystalline forms of alumina intermediategammaand alpha-alumina, beta-alumina trihydrate and alpha-aluminamonohydrate. The tobacco additives within the compass of my inventionare considered by competent contemporary authorities to be innoxiouswhen inhaled or otherwise orally administered. Tobacco compositions madein accordance with the subject invention are characterized by a smoothessentially bite-free taste when smoked. The smoke effluent from saidcompositions is distinguished by a tar content substantially lower thanthat of a smoking mixture including the same tobacco specie or speciesbut devoid of the novel additive. Other aluminous additives have beenintimately associated with smoking tobacco and the smoke efiiuent fromthe mixture analyzed by in vitro method capable of reproducing in vivosmoking conditions; it has been found that such additives do not producethe outstanding benefits which are realized by use of an additive withinthe scope of my invention. I have found, for example, that bauxite,which comprises gibbsite (alpha-alumina trihydrate) is not an effectiveadditive in either its naturally-occuring or thermally activated state.Furthermore, I have found that pure crystalline alphaalurnina trihydrateactually increases the tars generated from a given weight of tobacco.

In accordance with my invention a minor amount of additive selected fromthe above defined group of aluminous materials is intimately associatedwith tobacco. From about 1 to 15% of additive, based on the weight oftobacco may be used in tobacco compositions of my invention althoughfrom about 2 to 10% will ordinarily be used. The optimum quantity ofaluminous additive will vary with specie and method of preparationthereof and will also vary with the type and quality of tobacco used andthe moisture content of the composition. The tobacco may be leaf,reconstituted tobacco or mixtures thereof and may be treated and cut foruse in cigarettes, pipes or cigars. However maximum benefits areordinarily attained when the novel additive is employed in a cigaretteand, accordingly, the invention will be described with particularreference to cigarettes and tobacco mixtures suitable for use incigarettes.

The various aluminas and hydrates thereof which are within the compassof my invention are well described in a publication by Aluminum Companyof America, Russell, Allen S., Alumina Properties, Technical Paper No.10 (1953).

Alpha-alumina monohydrate occurs naturally as the mineral boehmite.Under suitable conditions it may be prepared by partial dehydration ofthe trihydrate of alphaalurnina. The conversion is rapid when thetrihydrate is ture not far'below the fusion temperature.

a 3 heated in dilute aqueous solution at about 200 C. or by heating thetrihydrate rapidly above about 450 C.

Beta-alumina trihydrate, a synthetically prepared compound, has nonaturally-occurring counterpart. The ma terial is sometimes calledbayerite because of the mistaken assumption of past researchers that itis the form of hydrated alumina produced in the well known Bayerprocess. Beta-alumina trihydrate is produced by several methodsincluding the neutralization of a sodium aluminate with carbon dioxideat -30" C. under conditions such as to eifect rapid precipitation.It'has been found that slow precipitation does not produce the desiredcompound. Beta-alumina trihydrate may also be formed by precipitation ofalumina by alkali from solutions of aluminum salts.

Unfused alpha-alumina exists in various crystalline forms, one of themost useful of which in compositions within the scope of the instantinvention is tabular alumina. Tabular alumina is commercially preparedby calcining alumina from the Bayer process to a tempera- In the Bayerprocess bauxite is digested with hotcaustic solution to put the aluminainto solution as sodium aluminate. Aluminum'trihydrate is precipitatedfrom solution and is treated by calcination and reduction to yield thepure aluminum. Tabular alumina has the crystal form of corundum andretains its porosity to elevated temperatures in the range of the fusionpoint of alumina Other useful forms of alphaalumina include variouslyprepared crystalline materials which have not been subjected to fusion.Another particularly useful specie of alpha-alumina is prepared bycalcination of diaspore.

Gamma-alumina is not found in nature but is produced when thetrihydrates of alumina or the gamma-monohydrate are heated to a hightemperature to loose combined water and, on further heating to atemperature of the order of 900 C. form crystalline gamma-alumina,

' a metastable alumina, which, on further heating to temperatures above1000 C. converts to alpha-alumina. The transition temperature fromgamma-alumina to alphaalumina. is not sharply defined and intermediateforms of alumina may be recognized by X-ray diifraction patterns, suchintermediate forms being useful in tobacco compositions of my invention.Gamma-alumina "and transitional intermediate aluminas are characterizedby a water content which is finite but less than that corresponding tothe 'monohydrate. Gamma-alumina may also be prepared by the controlledoxidation of aluminum.

The aluminous additive is preferably incorporated in cigarette tobaccoin comminuted form, usually less than about 300-mesh and preferablyhaving a preponderating portion less than about 10 microns. -In general,the more finely divided the aluminous additive the greater the adhesionto tobacco particles. Of course the particular particle size used in acomposition will depend on such factors as moisture content, presence oftacky humectants or other hinder, mode of application to tobacco, sizeof tobacco particles, presence and nature of filter-device and locus ofadditive placement.

The aluminous additive may be distributed substantially uniformlythroughout the body of the cigarette or, as in an embodiment of theinvention, the material may be placed selectively within the cigaretteto efiect maximum benefits. Accordingly, the material may beadvantageously gradated throughout the cigarette with maximum contentproximate to the inhaling end where, during the smoking of thecigarette, maximum tar deposition is encountered.

A filter, either of the well-known type which is integral with thesmoking unit or of the holder type including a filter, is preferablyemployed in a smoking unit comprising tobacco and aluminous additive.The filter may be fibrous and/or include adsorbents such as silica, clayor the like. The purpose of the filter is to prevent any inspiration offinely-divided particles which may occur if the smoking unit issubjected to dry warm weather for prolonged periods. The filter imposesa bed of material capable of entraining the particle which mightotherwise be drawn into the smoker mouth. However, by proper selectionof moisture content and, in some cases, inclusion of about 24% (based onthe weight of the tobacco) of humectant or by otherwise bonding theadditive to the tobacco surface the filter may be omitted. When adhesionof the additive to the tobacco is inadequate a binder may be used toimprove adhesion between the tobacco and the additive.

The following embodiments of my invention are given only for the sake ofmore fully illustrating the invention and are not to be construed aslimiting the scope thereof.

Example I Example II Another composition of my invention is prepared byspraying an aqueous slurry of finely-divided boehmite onto whole leaftobacco shreds blended with reconstituted shredded tobacco to deposit 10parts of boehmite on parts of blended tobacco shreds.

Example III The invention is further illustrated by substitutingbetaalumina trihydrate, finely-divided, for the tabular alumina ofExample I.

Example IV Gum arable solution is used to bind 'comminuted microporousgamma-alumina to tobacco leaf. Gamma-alumina suspended in a dilute gumarabic solution is used to coat stemmed aged tobacco leaf and suflicientmoisture is evaporated to mix the gamma-alumina to the leaf. The leafthus treated may be suitably cut and processed for use in cigarette,pipe or cigar smoking compositions.

It will be understood that the invention is not limited to compositionsprovided by dry dusting of additive onto tobacco since the additive maybe associated with the to bacco by spraying in water or a suitablebinding liquid or by immersion techniques. Furthermore it is within thescope of the invention to include the additive in reconstituted tobaccoby forming comminuted tobacco and aluminous additive into a coherentmass in the presence of a suitable binder.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore, only such limitations should be imposed asare indicated in the appended claims.

I claim: 1. A smoking mixture comprising a major portion of tobacco andintimately associated with at least a portion talline form of aluminaintermediate gammaand alphaalumina.

5. The smoking mixture of claim 1 in which said finelydivided aluminousmaterial comprises beta-alumina trihydrate.

6. The smoking mixture of claim 1 in which said finelydivided aluminousmaterial comprises alpha-alumina monohydrate.

7. A smoking mixture comprising a major portion of particulated tobaccoand dispersed throughout said tobacco and intimately associatedtherewith from 1 percent to 15 percent by weight of at least onefinely-divided crystalline aluminous material selected from the groupconsisting of unfused alpha-alumina, gamma-alumina, transitionalcrystalline forms of alumina intermediate gammaand alpha-alumina,beta-alumina trihydrate, and alpha-alumina monohydrate.

8. The smoking mixture of claim 7 in which said finelydivided aluminouscomprises unfused alpha-alumina.

9. The smoking mixture of claim 7 in which said finely-divided aluminousmaterial comprises gammaalumina.

10. The smoking mixture of claim 7 in which said finely-dividedaluminous material comprises a transitional crystalline form of aluminaintermediate gammaand alpha-alumina.

11. The smoking mixture of claim 7 in which said finely-dividedaluminous material comprises beta-alumina trihydrate.

12. The smoking mixture of claim 7 in which said finely-dividedaluminous material comprises alpha-alumina monohydrate.

13. A smoking unit comprising a column of tobacco and dispersedthroughout at least a portion of said tobacco and intimately associatedtherewith from 1 percent to 15 percent by weight of at least onefinely-divided crystalline aluminous material selected from the groupconsisting of gamma-alumina, alpha-alumina, transitional crystallineforms of alumina intermediate gammaand alpha-alumina, beta-aluminatrihydrate and alpha-alumina monohydrate.

14. A cigarette comprising a column of particulated tobacco, said columnterminating in a filter-tip, and distributed throughout at least thatportion of said column contiguous said filter-tip from 1 percent to 15percent by weight of at least one finely-divided crystalline aluminousmaterial selected from the group consisting of unfused alpha-alumina,gamma-alumina, transitional crystalline forms of alumina intermediategammaand alpha-alumina, beta-alumina trihydrate and alpha-aluminamonohydrate.

15. The cigarette of claim 14 in which the aluminous material comprisesgamma-alumina.

16. The cigarette of claim 14 in which the aluminous material comprisesunfused alpha-alumina.

17. The smoking mixture of claim 14 in which said finely-dividedaluminous material comprises a transitional crystalline form of aluminaintermediate gammaand alpha-alumina.

18. The smoking mixture of claim 14 in which said finely-dividedaluminous material comprises beta-alumina trihydrate.

19. The smoking mixture of claim 14 in which said finely-dividedaluminous material comprises alpha-alumina monohydrate.

References Cited in the file of this patent UNITED STATES PATENTS1,972,718 Sharlit Sept. 4, 1934 2,003,690 Le-wton June 4, 1935 2,007,407Sadtler July 9, 1935 2,063,014 Allen Dec. 8, 1936 2,786,471 GraybealMar. 26, 1957 2,839,065 Milton June 17, 1958 FOREIGN PATENTS 666,308Great Britain Feb. 6, 1952 OTHER REFERENCES The Aluminum Industry,Aluminum and Its Production, (text) by Edwards, Frary and Jeffries, 358pp., pub. by McGraw-Hill Book Co., New York. Pp. 166 to 169 especiallycited.

1. A SMOKING MIXTURE COMPRISING A MAJOR PORTION OF TOBACCO ANDINTIMATELY ASSOCIATED WITH AT LEAST A PORTION OF SAID TOBACCO FROM 1PERCENT TO 15 PERCENT BY WEIGHT OF AT LEAST ONE FINELY-DIVIDEDCRYSTALLINE ALUMINOUS MATERIAL SELECTED FROM THE GROUP CONSISTING OFUNFUSED ALPHAALUMINA, GAMMA-ALUMINA, TRANSITIONAL CRYSTALLINE FORMS OFALUMINA INTERMEDIATE GAMMA- AND ALPHA-ALUMINA, BETAALUMINA TRIHYDRATEAND ALPHA-ALUMINA MONOHYDRATE.